Explicit unload() 'destructor'

brmdoor_nfc.cpp

@@ -1,4 +1,5 @@
 #include <string>
+#include <cassert>
 
 #include <nfc/nfc.h>
 #include <nfc/nfc-types.h>
@@ -13,7 +14,8 @@ NFCDevice::NFCDevice() throw(NFCError):
     pollPeriod(2),
     _nfcContext(NULL),
     _nfcDevice(NULL),
-    _opened(false)
+    _opened(false),
+    _unloaded(false)
 {
     nfc_init(&_nfcContext);
     if (_nfcContext == NULL) {
@@ -26,7 +28,7 @@ NFCDevice::NFCDevice() throw(NFCError):
 NFCDevice::~NFCDevice()
 {
     close();
-    nfc_exit(_nfcContext);
+    unload();
 }
 
 void NFCDevice::open() throw(NFCError)
@@ -55,11 +57,26 @@ void NFCDevice::close()
         return;
     }
 
+    assert(_nfcDevice);
+
     nfc_close(_nfcDevice);
     _nfcDevice = NULL;
     _opened = false;
 }
 
+void NFCDevice::unload()
+{
+    if (_unloaded) {
+        return;
+    }
+
+    assert(_nfcContext);
+
+    nfc_exit(_nfcContext);
+    _nfcContext = NULL;
+    _unloaded = true;
+}
+
 std::string NFCDevice::scanUID() throw(NFCError)
 {
     int res;

brmdoor_nfc.h

@@ -71,12 +71,18 @@ public:
     /** Open device explicitly. May be useful after explicit close */
     void open() throw(NFCError);
 
-    /** Returns true iff device was opened */
-    bool opened() const {return _opened;}
+    /** Returns true iff device was opened and not unloaded. */
+    bool opened() const {return _opened && !_unloaded;}
 
     /** Close reader. You need to reopen before reading again */
     void close();
 
+    /** 
+     * Unload all structures, close device. It's kind of explicit destructor
+     * since we can't be sure the destructor will be called in Python.
+     */
+    void unload();
+
     /** 
      * Specifies the number of polling (0x01 – 0xFE: 1 up to 254 polling, 0xFF:
      * Endless polling)
@@ -106,6 +112,9 @@ protected:
     /** Whether device has been successfully opened */
     bool _opened;
 
+    /** Whether device and its internal libnfc structures have been unloaded */
+    bool _unloaded;
+
 };
 
 

runme.py

@@ -11,5 +11,6 @@ try:
 	print "Closing device"
 	nfc.close()
 	print "Device is opened:", nfc.opened()
+	nfc.unload()
 except NFCError, e:
 	print "Reading UID failed:", e.what()